Electron tube having tamper-detectable label attached thereto

ABSTRACT

An electron tube, such as a television-picture tube, comprising a sealed envelope having a cathode and an anode therein, a label comprising a dye-stainable backing adhered to the external surface of said envelope, the label and a layer including a solvent-soluble dye contiguous with at least a portion of a surface of the backing.

United States Patent Deal et al.

[451 Aug. 1,1972

[54] ELECTRON TUBE HAVING TAMPER- DETECTABLE LABEL ATTACHED THERETO [72] Inventors: Samuel Broughton Deal, Lancaster;

Donald Walter Bartch, Columbia,

both of Pa. [73] Assignee: RCA Corporation [22]. Filed: Aug. 21, 1970 211 App]. No.: 65,802

521 Us. Cl. ..40/2.2, 283/8 [51] Int. Cl. ..oosr 3/02 [58] Field of Search ..283/8, 9, 18, 21; 40/2, 2.2, 40/125 A [56] References Cited UNITED STATES PATENTS 2,198,162 4/1940 Greenwald ..40/2.2 X

Whitehead ..40/ 2.2

2,588,067 3/1952 2,780,015 2/1957 Whitehead ..40/ 2.2 3,364,049 1/1968 Deak et al. ..283/8 R 3,442,038 5/1969 Boyce ..40/ 2.2 3,487,567 1/1970 Waybright ..40/ 2.2

Primary Examiner-Robert W. Michell Assistant Examiner-Wenceslao .l. Contreras Attorney-Glenn H. Bruestle 57] ABSTRACT An electron tube, such as a television-picture tube, comprising a sealed envelope having a cathode and an anode therein, a label comprising a dye-stainable backing adhered to the external surface of said envelope, the label and a layer including a solvent-soluble dye contiguous with at least a portion of a surface of the backing.

9 Claims, 4 Drawing Figures PATENTEDAus 1 1912 3.680.236

35) I 3 WARRANTY p gfu ggubg WARNING-\ IIIIIIIHHII I IIIIIIIIIIIH" Hlllllllllll 3 lllllllllllll ABC COMPANY uuunum Fig.3. I Fig.4.

INVENTORS Samuel 8. Deal and Donald W Barfch.

ATTORNEY ELECTRON TUBE HAVING TAMPER- DETECTABLE LABEL ATTACHED THERETO BACKGROUND OF THE INVENTION This invention relates to an electron tube having a label thereon which indicates whether an attempt has been made to remove it with the aid of an organic solvent.

An electron tube, for example, a television-picture tube, may carry a warranty from the manufacturer that it will continue to perform for a stated period of time after purchase, for example, for two years. Thewarranty or an identifying mark may be carried on a label which is adhered to the outer or external surface of the tube. It is desirable to detect whether an attempt, successful or otherwise, has been made to remove the label with the aid of an organic solvent in order to transfer it to another tube. Most commercial labels are easily removable from the tube with the aid of an organic solvent. The solvent softens the adhesive which adheres the label to the tube, and then the label can be lifted ofi the tube with the aid of a razor blade. Then, the label may be transferred to another tube where the tampering is not easily detected. Polymerized-in-place adhesives can be used to provide tamper-proof characteristics, but these labels are difficult and expensive to use in a mass-production process.

SUMMARY OF THE INVENTION The novel electron tube comprises a sealed envelope having a cathode and an anode therein and a label adhered to the external surface of the envelope. The label comprises a stainable backing, such as paper or other cellulosic material. A layer including a solvent-soluble dye is contiguous with at least a portion of the surface of the backing. The dye-containing layer maybe some or all of the printed indicia on the outer surface of the label, or it may be in the adhesive layer that attaches the label to the tube. Should a solvent be applied to the label subsequent to its adherence to the tube, some of the dye dissolves and stains the backing with the characteristic color of the dye. The stain may completely color the backing or may simply bleed or smear into adjacent areas of the backing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially broken, longitudinal view of a cathode-ray tube including a warranty label attached to the external surface of the funnel portion thereof.

FIG. 2 illustrates a label having various printed indicia thereon, prior to application to the tube of FIG. 1.

1 FIG. 3 is an enlarged sectional view partially symbolic through a fragment of the tube of FIG. 1 along section lines 33.

FIG. 4 is an enlarged sectional view through a fragment of another tube similar to the tube illustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The cathode-ray tube illustrated in FIG. 1 includes an evacuated envelope, designated generally by the nunieral 21, which includes a neck section 23 integral with a funnel section 25 and a faceplate or viewing panel 27 joined to the funnel section 25 by a seal 29,

preferably of a devitrified glass. A luminescent screen 31 resides on the interior surface of the faceplate 27. The screen 31 includes a layer of phosphor material and a light-reflecting coating, as of aluminum, applied to the phosphor layer. The luminescent screen 31, when suitably scanned by an electron beam from a gun 33, is capable of producing a luminescent image which may be viewed through the faceplate 27. Inasmuch as the invention is concerned primarily with the label adhered to the funnel; the electronemitting components and other parts normally associated with neck and funnel portions 23 and 25 are omitted or shown schematically.

A label 35, shown in greater detail in FIGS. 2 and 3, is attached to the funnel portion 25 by an adhesive 43. The label 35 is comprised of a dye-stainable backing, for example, paper, and a printed indicia 37 and 39 thereon. The one type of indicia is solvent smearable and consists essentially of pigment particles such as carbon, a solvent-soluble binder for the particles and a dye in the binder. The other type of indicia 39 is similar in'constitution but contains no dye and is not solvent smearable. The label is adhered to the outer surface 41 of the funnel 25 with a water-insoluble adhesive 43 which is preferably permanently set.

The tube 21 is fabricated by any of the methods known in the art. At the conclusion of tube fabrication, the label 35 is applied to the external surface 41 of the funnel 25 with a water-insoluble adhesive. Any attempt to remove the label with the aid of an organic solvent causes the dye in the one type of indicia 37 to bleed or smear dye into the backing, leaving a telltale dye stain around the indicia 37. Prolonged exposure to an organic solvent causes the entire backing to become stained.

An ink that may be used to produce solvent-smearable indicia consists of the following:

30 milliliters of a 2 weight percent solution of a polyvinyl acetate resin (such as D383 sold by Rohm and Haas Chemical Company, Philadelphia, Pa.) in acetone 1 gram Oil Red 0 dye 10 grams inorganic black pigment (such as No. 9530 sold by B. F. Drakenfeld Company, New York, N. Y.)

This is a black ink which produces normally black indicia and produces a red smear or stain on the backing when organic solvents are applied to the backing.

Another ink that may be used to produce solventsmearable indicia consists essentially of:

. 30 milliliters of a 2 weight percent solution of a I polyvinyl acetate resin (such as D383 sold by Rohm and Haas Chemical Company, Philadelphia, Pa.) in acetone l gram Oil Red 0 1 gram Monostral Blue BW (such as BP-l92 sold by du Pont Chemical Company, Wilmington, Del.) 10 grams inorganic blue pigment (such as 10334 sold by B. F. Drakenfeld Company, New York, N. Y.) This is a blue ink that produces blue indicia and a red smear when organic solvents such as acetone, ethyl alcohol and kerosene, are applied to the backing.

In the foregoing embodiments, the dye is in a layer that is contiguous with the outer surface of the layer. In another embodiment of the invention, the dye is in a layer that is contiguous with the inner surface of the label. An example of this is illustrated in FIG. 4 in which a label 35a is adhered to the outer surface 41 of the funnel 25 with an adhesive 43a that contains a solvent-soluble dye. The printed indicia 39 have no dye in their composition. When a solvent is applied to the adhered label, some of the dye dissolves from the adhesive layer and bleeds into the backing producing a dye stain thereon.

The backing used for the label may be of any stainable or dye-absorbent material. Such backings are preferably porous or have a porous surface layer. Materials such as paper, cloth, and other fibrous cellulosic materials are preferred; although plastic and anodized metal may also be suitable.

The pigment used in the indicia may be inorganic, organic, metallic, nonmetallic or ceramic. The preferred pigments are inorganic, such as carbon black and titanium dioxide. Also preferred are inorganic ceramic materials, such as 10319 Cerulean Blue, 10348 Kelly green and 10367 Deep Red, all sold by B. F. Drakenfeld Company. The binder may be any of the usual pigment binders which are solvent soluble and water insoluble. Some suitable binders are polyvinyl acetates, polyvinyl butyrals, polystyrenes and polyacrylates.

The dye may be any organic solvent-soluble dye. The color is a matter of preference and is determined by the particular needs of the user. Some suitable dyes are the dyes given in the examples of inks and in addition, Oil Blue N, which may be used for producing a blue stain; and Naphthol Green B, which may be used for producing a green stain.

The ingredients are combined in any of the usual ways. For example, start with a solution or emulsion of the binder in a solvent and then mix in the pigment and dye. Then, the ink is used for printing or otherwise depositing a layer or markings upon the backing in the case of the example shown in FIGS. 1 to 3. After the label is dried, it is adhered to the tube with an adhesive.

We claim:

1. An electron tube comprising a sealed glass .envelope having a cathode and an anode therein, a label adhered to the external surface of said envelope, said label comprising a dye-stainable backing, and a layer containing a solvent-soluble dye contiguous with at least a portion of a surface of said backing.

2. The tube defined in claim I wherein said dye-containing layer is deposited in selected configurations on the outer surface of said backing.

3. The tube defined in claim 2 wherein said backing is a fibrous cellulosic material and said layer includes a blue dye.

4. The tube defined in claim 2 wherein said backing is a fibrous cellulosic material and said layer includes a green dye.

5. The tube defined in claim 2 wherein said backing is a fibrous cellulosic material and said layer includes a red dye.

6. A television-picture tube comprising a sealed glass envelope and a label adhered to the outer surface of said envelope, said label comprising a paper backing having markings thereon comprised of pigment particles, a solvent-soluble binder for said particles and a dye in said binder.

7. The tube defined in claim 6 wherein said dye is Oil Red N 8. The tube defined in claim 6 wherein said dye 1s 01] Blue N.

9. The tube defined in claim 6 wherein said dye is Naphthol Green B. 

1. An electron tube comprising a sealed glass envelope having a cathode and an anode therein, a label adhered to the external surface of said envelope, said label comprising a dye-stainable backing, and a layer containing a solvent-soluble dye contiguous with at least a portion of a surface of said backing.
 2. The tube defined in claim 1 wherein said dye-containing layer is deposited in selected configurations on the outer surface of said backing.
 3. The tube defined in claim 2 wherein said backing is a fibrous cellulosic material and said layer includes a blue dye.
 4. The tube defined in claim 2 wherein said backing is a fibrous cellulosic material and said layer includes a green dye.
 5. The tube defined in claim 2 wherein said backing is a fibrous cellulosic material and said layer includes a red dye.
 6. A television-picture tube comprising a sealed glass envelope and a label adhered to the outer surface of said envelope, said label comprising a paper backing having markings thereon comprised of pigment particles, a solvent-soluble binder for said particles and a dye in said binder.
 7. The tube defined in claim 6 wherein said dye is Oil Red N.
 8. The tube defined in claim 6 wherein said dye is Oil Blue N.
 9. The tube defined in claim 6 wherein said dye is Naphthol Green B. 